add separate port_size and mach_port_name_size definitions

* cpu.sym: retrieve size of vm_offset_t and mach_port_name_t from
  gnumach headers at compile type.
* global.{c,h}: add port size as a variable and initialize it to the
  port name size.
* lexxer.l: apply port or port name size to the corresponding types,
  instead of using the word size.
* parser.y: update port size if we're generating for kernel-space
  (server or client). Also re-initialize default port types to account
  for this change.
* type.c: use port size instead of word size in default port types and
  runtime checks.

There are many assumptions about mach_port_t:
 - on kernel side, its size is the same as a pointer. This allows to
   replace the port name with the address of the corresponding data
   structure during copyin in mach_msg()
 - in mig, this is also the "word size", which is derived from gnumach
   headers as the size of integer_t
 - its size is also the same as natural_t, so it's possible to model
   structures like mach_port_status_t as an array of integer_t in
   mig. This is convenient since arrays and structures can't have
   mixed types.
 - its size is always the same as the port name size

This patch does not change the current behaviour on 32-bit kernels,
but allows for some of these assumptions to be broken on 64-bit
kernels. This is needed to have 32-bit port names on 64-bit kernels
and be able to support a 32-bit userspace.  It still leaves the choice
for a 64-bit userspace, if all integer_t and natural_t are to be
extended to 64 bit.

However keeping 32-bit port names seems to be the right thing, based on
previous discussions [1], even for a 64-bit kernel.

The only assumption kept is that in kernel-space ports are always the
size of a pointer, as they refer to a data structure and not to a
specific port name.  To ensure this is true for various user/kernel
combinations, we dynamically change the port size if we're generating
code for kernel-space server or clients, and keep the size of a port the
same of a port name for user-space servers and clients.

[1] https://lists.gnu.org/archive/html/bug-hurd/2012-04/msg00000.html

Signed-off-by: Luca Dariz <luca@orpolo.org>
Message-Id: <20220403150020.120799-2-luca@orpolo.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/global.h b/global.h
index 8dbb6fd..cadd7e7 100644
--- a/global.h
+++ b/global.h
@@ -67,6 +67,9 @@ extern string_t InternalHeaderFileName;
 extern string_t UserFileName;
 extern string_t ServerFileName;
 
+extern int port_size;
+extern int port_size_in_bits;
+
 extern void more_global(void);
 
 #ifndef NULL